The Battle of Normandy, codenamed Operation Overlord, began with the amphibious Allied landings at Normandy, France, early in the morning of June 6, 1944, and continued into the following weeks with a land campaign to establish, expand, and eventually break out of the Normandy bridgehead. In the English-speaking world, it remains the best-known battle of World War II.

The foreshore area had been extensively fortified by the Germans as part of their Atlantic Wall defences. It was manned with a haphazard collection of troops: mainly Germans who (usually for medical reasons) were not considered suitable for active duty on the Eastern Front[?], and other nationalities (mainly Russians) who had agreed to fight for the Germans rather than endure a prisoner of war camp. Some of the area immediately behind the coastline had been flooded by the Germans as a precaution against parachute assault.

Prior to the battle, the Allies had carefully mapped and tested the landing area, paying particular attention to weather conditions in the English Channel. The weather conditions at the only time when the landings were practicable (because of tide and moonlight considerations) were particularly severe. The German forces were not expecting the landings to occur because of this.

In addition to the main beachhead assaults, troops were parachute dropped behind enemy lines and these were further supported by troops arriving in gliders at key points. Coordinated activities with the French resistance forces, the Maquis, helped disrupt Axis lines of communications.

Additionally, the Allies made extensive use of deception in a series of complex plans under the overall rubric of Bodyguard. Key to this overarching strategic effort was the local feint using dummy weaponry and forces to simulate a landing further east in the Pas de Calais, Operation Fortitude. This drew the best German tank and infantry divisions in the west away from Normandy. Also in the Allies favor, much of the German command had been called back to (Paris?) for wargames and thus were not present on the critical first day, when the allies could have most easily been thrown off the beaches.

Once the beachhead was established, two artificial Mulberry Harbours[?] were towed across the English Channel in segments. One was constructed at Arromanches[?], the other at Omaha Beach. For a short while, this facilitated the landing of heavy weaponry and materials, but they were soon lost to storms, and by far the major part of the Allied materiel came over the beaches.

The Normandy landings were long foreshadowed by a considerable amount of political manoeuvring amongst the allies. There was much disagreement about timing, appointments of command, and where exactly the landings were to take place. The opening of a second front had been long postponed (it had been initially mooted in 1942), and had been a particular source of strain between the allies. Churchill in particular was concerned to land and advance in Europe before the Soviet forces rolled up and gained control over swathes of territory.

The appointment of Montgomery was questioned by some Americans, who would have preferred the urbane General Alexander[?] to have commanded the land forces. Montgomery himself had doubts about the appointment of Eisenhower because Eisenhower had very little field experience. (In the event, however, Montgomery and Eisenhower cooperated to excellent effect in Normandy: their well-known disagrements came much later.)

Normandy presented serious logistical problems, not the least of which being that the only viable port in the area, Cherbourg, was heavily defended and many among the higher echelons of command argued that the Pas de Calais would make a more suitable landing area on these grounds alone.

Although ultimately successful, the Normandy landings were extremely costly in terms of men and material. The failure of the 3rd Division to take Caen, an overly ambitious target, on the first day was to have serious repercussions on the conduct of the war for well over a month, seriously delaying any forward progress. The fortuitous capture of Villers-Bocage followed by the failure to reinforce it, and its subsequent recapture by the Germans, was again to hamper any attempt to extend the Caen bridgehead and push on. By D+11, June 17th, the Allies worst fears had materialised: the assault had stagnated.

A lot of the problem came down to the nature of the terrain in which much of the post-landing fighting took place, the bocages. These were essentially small fields separated by high earth banks covered in dense shrubbery, which were eminently defensible.

The toehold that the allies established at Normandy was vital for the Western Allies (the British Commonwealth and the US) to bring the war to Germany's front door. It has been pointed out that Soviets alone had the capacity to crush Germany by this time, and that this battle was unnecessary for the purpose of defeating the German Reich.
By the time of D-Day, the Red Army was steadily advancing towards Germany and four fifths of the German forces were in the East. In France, the Allies faced only about 20% of the German army in France.
Yet given the Soviet's claim over Eastern Europe, one could ask if the result would have been a complete occupation of Europe by communist forces. American and British presence helped define the extent that communism would spread, and ensure that democracy would be safe in Western Europe. Thus the battle of Normandy needs to be understood both within the context of WWII and in that of the Cold War that would follow.